Nanoporous metals prepared by controlled chemical or electrochemical corrosion of alloys can provide prototypical manifestations of bulk nanostructured material. Samples are readily prepared with dimensions at the millimeter or centimeter scale, while at the same time the microstructure is a homogeneous array of interpenetrating solid skeleton phase and pore channels with a characteristic size that can reach down to below 5 nm. The interest in nanoporous metals as functional materials derives from recent observations of unique materials behavior resulting from their extremely small structure size and their open porosity with large volume-specific surface area. As an example, this article discusses the possible use of nanoporous metal for actuation.